AGATES. 
165 
o5a and dob. Segments of a : 
large pear-shaped Amygdaloid,, j 
of regular form, nearly filled with 
successive deposits of amethystine 
quartz, interrupted by concentric 
layers of chalcedony coloured by 
hydrous oxide of iron. Calc Spar 
is associated with some of the 
earlier quartz deposits. 
56. Chalcedony Amygdaloid i 
provided with several different 
inlets of infiltration, showing 
clearly on the polished face the 
circular arrangement of the infil¬ 
trated substance. 
From the decomposed Melaphyre 
of the River San Leopoldo, in 
Uruguay, 3Ionte Video. 
56a and 56b. Segments of an 
Amygdaloid of Chalcedony and 
Amethystine Quartz, exhibiting 
several inlets of infiltration. 
Montrose. i 
57. Section of an Amygdaloid i 
of Chalcedony and Amethyst, I 
showing two distinct inlets of in¬ 
filtration with sediments so similar 
as to be probably contempora¬ 
neous. 
Uruguay. 
58 and 59. Sections of two j 
Amygdaloids, each with one inlet i 
of infiltration. ; 
59a. Section of an Amygdaloid j 
of Chalcedony and Amethystine ] 
Quartz, showing distinct inlet of 
infiltration. 
59b. Section of a Chalcedony 
Amygdaloid, exhibiting inlet of 
infiltration. 
60. Fragment of an Amygda- i 
LOiD, the final deposit being hy- ! 
drous oxide of iron mingled with 
particles of Chalcedony. 
Uruguay. 
61. Segment of an Amygda¬ 
loid with Chalcedony and Ame¬ 
thyst, showing two inlets of infil¬ 
tration. Artificially coloured as 
Onyx. 
Uruguay. 
62 and 63. Segments of AmyG'^ 
DALOIDS, with the inlets of infil¬ 
tration still open. Both specimens 
artificially heightened in colour. 
Uruguay. 
63a. Segment of Amygdaloid 
of Amethystine Quartz and Chal¬ 
cedony, with inlet of infiltration 
still open. Artificially coloured. 
63b. Concentric deposits of 
Chalcedony, natural colour. 
63c. Section from the same 
specimen, artificially coloured by 
carbon. 
63d. Concentric deposits of 
Chalcedony, colour heightened. 
63e. Section of Chalcedony and 
Agate-Jasper, with Amethystine 
Quartz, the inlets of infiltration 
still open. 
64 and 65. Two segments of 
Amygdaloids, with one and two 
inlets of infiltration respectively, 
artificially coloured as Carnelian. 
66 and 67. Amygdaloid with 
several inlets of infiltration, some 
of which have been choked up 
before the others. 
Uruguay. 
67a. Chalcedony, with several 
irregular systems of infiltration. 
68. Segment of Amygdaloid 
showing many systems of infil¬ 
tration. 
68a. Polished Slab of Chalce¬ 
dony, showing several systems of 
infiltration. 
69. Segment of Amygdaloid, 
consisting of Agate-Jasper, Chal¬ 
cedony, and Amethyst, with two 
distinct inlets of infiltration. 
Galgenherg. 
70. A similar Amygdaloid, 
which after filling has been fissured. 
Galgenherg. 
71. Segment of Amygdaloid, 
consisting of Chalcedony and 
Amethyst, with inlets of infiltra¬ 
tion obscure. 
Galgenherg, 
